Air handling systems for the intake and distribution of air within a building are well known. They generally comprise an air intake device positioned at the intake end of a ductwork system, and some form of air pump, for example, a fan, that will induce air flow into the inlet and through the ductwork system to points of distribution within a building. The moving air may be processed by heating devices, cooling devices, dehumidifying devices and/or humidifying devices, as is desired. The air is then discharged through one or more discharges at desired locations within the building.
Outside air is normally drawn into the building. The air is brought through an intake device which, is designed to reduce the amount of liquid water, e.g., rain, that might try to enter the inlet of the intake device. Typically, this is done through the use of upwardly and inwardly inclined louvers. The incoming air impinges on the louvers and entrained liquid water will impinge on the louvers and be collected in a collection pan for subsequent discharge through one or more drains. The air speed across the louvers is such as to assist in the impingement of the water on the louvers and its subsequent collection and draining. If the air flow is too fast, the liquid water may be carried past the louvers and into the remainder of the air handling system. This can present several problems, including damage to moisture sensitive materials and equipment, and provide an environment for microbial growth within the air handling system.
The construction and operation of such systems are well known and generally effective. However, frozen water in the form of snow or sleet and in particular snow may, because of its properties, bypass collection at the louvers and enter the air handling system, thaw, and create problems similar to the intake of liquid water. Various attempts have been made to solve this problem. For example, U.S. Pat. No. 5,791,984 discloses an air handling system with snow removal capabilities. It utilizes a mesh pad interposed in the flow path immediately downstream of the louvers. Snow will impinge on the mesh pad which is heated by a heater to effect melting of the snow for subsequent collection and drainage from the air intake. However, this device has had its drawbacks. The mesh pad tended to plug up with snow in the upper portion rendering that portion impervious to or restricted flow through thereby elevating the flow rate through the remaining open portion of the flow path, forcing the water thru the pad requiring more energy to move the needed amount of air.
Air inlet sections of air handling systems tend to be short in the direction of flow, on the order of two feet or less, providing limited space for added air handling devices or other modifications. There is thus a need for an improved air intake device of an air handling system that will reduce the amount of frozen water entering the air handling system downstream of the air intake.